1. Field of the Invention
This invention relates to a group of compounds classified in the field of organic chemistry as furopyridinones and furopyrazinones useful as color formers in pressure-sensitive carbonless duplicating systems and thermal marking systems, to processes for the preparation thereof and to pressure-sensitive duplicating systems and thermal marking systems containing the same.
2. Description of the Prior Art
Several classes of organic compounds of widely diverse structural types are known to be useful as color formers for carbonless duplicating systems. Among the more widely recognized classes are phenothiazines, for example, benzoyl leuco methylene blue; fluorans, for example, 2'-anilino-6'-diethylaminofluoran; phthalides, for example, crystal violet lactone, and various other types of color formers currently employed in commercially acceptable carbonless duplicating systems. Typical of the many such systems taught in the prior art are those described in U.S. Pat. Nos. 2,712,507, 2,800,457 and 3,041,289 which issued July 5, 1955, July 23, 1957 and June 26, 1962, respectively. Many of the color formers in the prior art, however, suffer one or more disadvantages such as low tinctorial strength, poor light stability, low resistance to sublimation and low solubility in common organic solvents.
The following appears to constitute the most pertinent prior art relative to the present invention.
U.S. Pat. No. 3,775,424, issued Nov. 27, 1973, discloses in most pertinent part a series of compounds reportedly employed in pressure-sensitive record material and mark-forming mainfold systems and having the formula ##STR1## wherein inter alia each X is ##STR2## and each R is hydrogen, an alkyl radical having 1 to 4 carbon atoms, an alkoxy radical having 1 to 4 carbon atoms or a phenyl radical.
Belgian Pat. No. 812,406 published July 1, 1974 discloses in most pertinent part a pressure-sensitive copying paper containing as a color former a compound having the formula ##STR3## or a mixture thereof wherein inter alia Y is hydrogen and one of A and A' is indolyl and the other is a nitrogen or sulfur-containing heterocyclic group.
3. Prior Publications
Belgian Pat. No. 862,217, published June 22, 1978, which corresponds essentially to pending U.S. patent applications Ser. Nos. 821,926 and 942,996, filed Aug. 4, 1977 and Sept. 18, 1978, respectively, in the names of Paul Joseph Schmidt and William Mo-Wei Hung, the inventors in the instant application, discloses a series of phthalides useful as color formers in pressure-sensitive carbonless duplicating systems, thermal marking systems and hectographic or spirit-reproducing copying systems and having the formula ##STR4## wherein:
Q is di-lower-alkylamino, nitro, halo or COX, where X is hydroxyl, benzyloxy, alkoxy having from 1 to 18 carbon atoms or OM where M is an alkali metal cation, an ammonium cation or a mono-, di- or tri-alkylammonium cation having from 1 to 18 carbon atoms;
n is 0; or 1 when Q is di-lower-alkylamino, nitro or COX; or from 1 to 4 when Q is halo;
Y.sub.1, Y.sub.2, Y.sub.3 and Y.sub.4 are the same or different and are hydrogen, halo, hydroxyl, lower-alkoxy, alkyl having from 1 to 9 carbon atoms, phenyl-lower-alkyl, COOR.sub.4 or NR.sub.5 R.sub.6, where R.sub.4 and R.sub.5 are hydrogen or lower-alkyl and R.sub.6 is hydrogen, lower-alkyl, cycloalkyl having from 5 to 7 carbon atoms or lower alkanoyl; Z is ##STR5## in which: R is hydrogen or non-tertiary alkyl having from 1 to 4 carbon atoms;
R.sub.1 is hydrogen, or non-tertiary alkyl having from 1 to 18 carbon atoms; PA1 R.sub.2 is hydrogen, phenyl or non-tertiary alkyl having from 1 to 4 carbon atoms; PA1 R.sub.3 is hydrogen, non-tertiary alkyl having from 1 to 4 carbon atoms or non-tertiary alkoxy having from 1 to 4 carbon atoms; PA1 R.sub.7 is hydrogen, halo, lower-alkyl, lower-alkoxy or di-lower-alkylamino; PA1 R.sub.8 is lower-alkyl; and PA1 R.sub.9 is lower-alkyl, benzyl, phenyl or phenyl substituted with a lower-alkyl or lower-alkoxy group. PA1 R.sub.4 is lower alkyl; PA1 R.sub.5 is lower alkyl or benzyl; PA1 R.sub.6 is hydrogen or non-tertiary alkyl having from 1 to 18 carbon atoms; and PA1 R.sub.7 is hydrogen, phenyl or non-tertiary lower alkyl.